Our laboratory has in the past year conducted runs at CHESS A1, F1 and F2, NSLS X4A, X12 and X25, as well as APS to extend the resolution and improve the quality of diffraction data for crystalline complexes involved in chaperonin mediated protein folding, signal transduction, transcriptional and translational regulation. During those trips we have obtained numerous complete high resolution data sets resulting directly in the determination of the following new structures: (1) progesterone ligand binding domain complexed with progesterone; (2) human estrogen receptor ligand binding domain complexed with estradiol; (3) the chaperonin GroEL/GroES/ADP complex; (4) the T. thermophilus EF-Tu/EF-Ts complex; and (5) a P. woesei ternary complex of the TATA-binding protein, TFIIB, and a DNA sequence containing a consensus TATA box at 2.1 (see publications section). Data recently collected at CHESS has been instrumental in solving all of the above structures. In addition a paper on the molecular mechanism for the role of phosphorylation in the regulation of hetereotrimeric G-Proteins by phosducin is also in preparation from data collected at CHESS on the phosphorylated form of phosducin. Other projects which are still in progress which have been significantly influenced by CHESS synchrotron data collection include the following: Chaperonin-Medicated Protein Folding: To understand the capacity of ATP to drive the GroEL-GroES reaction cycle, we wish to study relevant intermediates in the ATPase cycle. GroEL/GroES/(ADP)7/(AlFx)7 crystals diffract to 4 at our home source but only initial tests were done at the CHESS F1 line this year. Searching for optimal freezing conditions is in progress. Bovine Visual Arrestin: The arrestin crystals diffract to 3.0 resolution using synchrotron radiation (NSLS X-25 beamline and MacCHESS A-1 beamline). We have collected complete native data sets to 3.1 (C2221; a = 169, b = c = 191; crystal size: 0.2 x 0.2 x 0.03 mm3). Useful MAD, heavy atom and anomalous data sets for phasing have been collected at CHESS, X-25 and APS. Quaternary Complex of VP16 Acidic Activation Domain Complexed with hTBPc, hTFIIB on Promoter DNA. To date no high resolution structural information exists on a transcriptional activator domain bound to the preinitiation complex. Hence, this crystal structure will reveal the essential contacts made between a strong acidic activation domain and the basal machinery, resulting in transcriptional activation. The crystals diffract to about 4.0 on a home source (at 100 K). Several 2.6 native data sets (P21; a = 118.7, b = 122.2, c = 140.8, b = 113.0 ; crystal size: 0.4 x 0.1 x 0.05 mm3) were collected recently at CHESS F2 and F1 lines.